This invention relates generally to the manufacture of stators for electric motors. More particularly, the present invention relates to a method and apparatus for winding and forming dynamoelectric machine field windings, and particularly, final forming of stator coil end turns.
In many conventional dynamoelectric machines, for example fractional horsepower induction motors, the magnetic stator core comprises a stacked plurality of relatively thin laminations of magnetic material having a central bore which receives the rotor member of the machine. A plurality of slots extend radially inwardly from the bore for receiving the field coils of the machine, wherein such slots are defined by radially extending teeth. A predetermined number of turns of insulated wire conductor are arranged within such slots to form the excitation windings of the motor. These coils have end turn portions extending outside the slots axially beyond the sides or end faces of the stator core.
In the past, two different types of apparatus have been employed for placing dynamoelectric machine field windings in the slots of the stator core member. In the so-called coil-insertion or coil-injection apparatus, prewound coils are first placed on a circular array of elongated blades. The stator core is then positioned on the blades with the blades respectively engaging the inner ends of the stator core teeth, and the coils are then pushed bodily into the stator core member slots. The coils for use with such coil-insertion apparatus are typically formed by securing the free end of the wire to a coil form and then winding or wrapping the wire around the coil form as the wire is withdrawn from the source, the wire being placed in tension as it is being wound.
In the so-called in-place or gun winder, a free end of the wire is secured and a gun is oscillated through the bore of the core member thereby withdrawing the wire from a source and placing it directly in the desired slots. Since the free end of the wire is fixed, the wire is in essence wound around selected teeth which define the slots thereby placing the wire under tension.
After the coils have been placed within the stator core, the return ends of the coils extend out of the stator slots and beyond the ends of the stator core. For reasons of appearance as well as customer specifications, the coil ends need to be shaped into a particular desired configuration. Such shaping operations are conventionally referred to as forming or blocking operations and typically have included a preforming operation wherein the wire was moved out of the extended bore of the stator and a final forming operation in which the end wires were shaped into the desired configuration. In the past, the preforming and final forming operations consisted of two distinct operations wherein, during the preforming operation, a preforming arbor was inserted into and extended through the bore of the stator to push the wires back from the extended stator bore. After this preforming operation the stator was transferred to another machine for final forming of the wire.
Drawbacks associated with prior stator winding and forming apparatus and methods include performing the winding and forming operations at different stations under different procedures. Further, in some prior devices the coil end turn wires have tended to be pinched. Such pinching is likely to undesiveably damage the wire or the wire insulation. Accordingly, there is a need for a tool for winding and forming dynamoelectric machine field windings which is of relatively simple construction, lends itself to use in a so-called in-place or gun winder, and provides for the winding and forming of field windings in one continuous set of operations. Further, such a tool is needed which minimizes the possibility of damaging the insulation on the windings. The present invention fulfills these needs and provides other related advantages.